1. Field of the Invention
The present invention relates to a process, devices and taximeters equipped with these devices for avoiding fraud on the price indicated by the luminous display means of an electronic taximeter.
The technical sector of the invention is that of the construction of electronic taximeters with luminous display means.
2. Description of the Prior Art
Former mechanical taximeters comprising display means composed of rotating rollers are being progressively replaced by electronic meters comprising a luminous device for displaying the price of the fare, for example a liquid crystal or electroluminescent diode device or any other equivalent luminous display device.
An electronic taximeter is a measuring apparatus for determining the price to be paid by a client. An essential quality of such an apparatus is that those persons using it cannot cheat the client by making him/her pay a price higher than the legal price.
It has appeared that the luminous display devices of electronic taximeters could give rise to fraud by voluntary cut-off of the current supplying the taximeter.
The electronic circuits of taximeters are supplied with a d.c. voltage by the battery of the vehicle as long as the voltage delivered by this battery is greater than a threshold voltage below which the electronic circuits can no longer function normally. In order to avoid erroneous indications of price, electronic taximeters generally comprise a safety device which compares the voltage delivered by the battery with a reference voltage which corresponds to the safety threshold below which the electronic circuits would risk defective functioning. This safety device produces a signal as soon as the voltage delivered by the battery falls below the safety threshold and interrupts the functioning of the taximeter. However, accidental voltage drops of short duration may occur during a fare, for example if the battery discharges slightly and if the driver of the taxi actuates the starter to start up the engine again after an accidental or voluntary stoppage thereof. Such accidental voltage drops cause the extinction of the luminous display means and, when voltage returns to normal, these display means must resume metering at the value which had been displayed before extinction.
It will be recalled that the luminous display means are increased step by step by a set quantity or increment which is for example ten or fifty cents. This increment corresponds for example, depending on the tariffs applied, to a distance of 1/10 mile or 100 meters or to a waiting time of 50 seconds.
These particularities of functioning of electronic taximeters equipped with luminous display means have given rise to fraud. One type of fraud consists in switching on the meter before a client has been picked up, for a stationary period which is slightly less than the period which corresponds to an increment of the fare, so that the luminous display means remains at zero. The electrical supply of the taximeter is then cut off, and is re-established at the instant when the client enters the taxi and when the "free-busy" switch is maneuvered. At this moment, the normal picking up price appears on the display means and, only a few seconds later, this price is increased by an increment, so that the taxi driver obtains an extra increment for each fare.
Another fraud consists in recording a price on the taximeter before a client is picked up, then in cutting the electrical supply of the taximeter until a client enters the taxi, so that, at that moment, the luminous display means is extinguished.
The electrical supply of the taximeter is re-established at the same time as or just before the "free-busy" switch is maneuvered, so that at that moment a price appears on the luminous display means which is equal to the sum of the picking up price and the fraudulently recorded price. An inattentive client will not differentiate this price from the picking up price which should normally be displayed.